 /*******************************************************************************
  * Copyright (c) 2005, 2007 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/
 package org.eclipse.core.internal.jobs;

 import org.eclipse.core.runtime.jobs.IJobManager;
 import org.eclipse.osgi.service.debug.DebugOptions;
 import org.osgi.framework.Bundle;
 import org.osgi.framework.BundleContext;
 import org.osgi.service.packageadmin.PackageAdmin;
 import org.osgi.util.tracker.ServiceTracker;

 /**
  * The class contains a set of helper methods for the runtime Jobs plugin.
  * The following utility methods are supplied:
  * - provides access to debug options
  * - provides some bundle discovery functionality
  *
  * The closeServices() method should be called before the plugin is stopped.
  *
  * @since org.eclipse.core.jobs 3.2
  */
 class JobOSGiUtils {
     private ServiceTracker debugTracker = null;
     private ServiceTracker bundleTracker = null;

     private static final JobOSGiUtils singleton = new JobOSGiUtils();

     /**
      * Accessor for the singleton instance
      * @return The JobOSGiUtils instance
      */
     public static JobOSGiUtils getDefault() {
         return singleton;
     }

     /**
      * Private constructor to block instance creation.
      */
     private JobOSGiUtils() {
         super();
     }

     void openServices() {
         BundleContext context = JobActivator.getContext();
         if (context == null) {
             if (JobManager.DEBUG)
                 JobMessages.message("JobsOSGiUtils called before plugin started"); //$NON-NLS-1$
 return;
         }

         debugTracker = new ServiceTracker(context, DebugOptions.class.getName(), null);
         debugTracker.open();

         bundleTracker = new ServiceTracker(context, PackageAdmin.class.getName(), null);
         bundleTracker.open();
     }

     void closeServices() {
         if (debugTracker != null) {
             debugTracker.close();
             debugTracker = null;
         }
         if (bundleTracker != null) {
             bundleTracker.close();
             bundleTracker = null;
         }
     }

     public boolean getBooleanDebugOption(String option, boolean defaultValue) {
         if (debugTracker == null) {
             if (JobManager.DEBUG)
                 JobMessages.message("Debug tracker is not set"); //$NON-NLS-1$
 return defaultValue;
         }
         DebugOptions options = (DebugOptions) debugTracker.getService();
         if (options != null) {
             String value = options.getOption(option);
             if (value != null)
                 return value.equalsIgnoreCase("true"); //$NON-NLS-1$
 }
         return defaultValue;
     }

     /**
      * Returns the bundle id of the bundle that contains the provided object, or
      * <code>null</code> if the bundle could not be determined.
      */
     public String getBundleId(Object object) {
         if (bundleTracker == null) {
             if (JobManager.DEBUG)
                 JobMessages.message("Bundle tracker is not set"); //$NON-NLS-1$
 return null;
         }
         PackageAdmin packageAdmin = (PackageAdmin) bundleTracker.getService();
         if (object == null)
             return null;
         if (packageAdmin == null)
             return null;
         Bundle source = packageAdmin.getBundle(object.getClass());
         if (source != null && source.getSymbolicName() != null)
             return source.getSymbolicName();
         return null;
     }

     /**
      * Calculates whether the job plugin should set worker threads to be daemon
      * threads. When workers are daemon threads, the job plugin does not need
      * to be explicitly shut down because the VM can exit while workers are still
      * alive.
      * @return <code>true</code> if all worker threads should be daemon threads,
      * and <code>false</code> otherwise.
      */
     boolean useDaemonThreads() {
         BundleContext context = JobActivator.getContext();
         if (context == null) {
             //we are running stand-alone, so consult global system property
 String value = System.getProperty(IJobManager.PROP_USE_DAEMON_THREADS);
             //default to use daemon threads if property is absent
 if (value == null)
                 return true;
             return "true".equalsIgnoreCase(value); //$NON-NLS-1$
 }
         //only use daemon threads if the property is defined
 final String value = context.getProperty(IJobManager.PROP_USE_DAEMON_THREADS);
         //if value is absent, don't use daemon threads to maintain legacy behaviour
 if (value == null)
             return false;
         return "true".equalsIgnoreCase(value); //$NON-NLS-1$
 }
 }

